1/* SPDX-License-Identifier: GPL-2.0 */
2#include <linux/mount.h>
3#include <linux/seq_file.h>
4#include <linux/poll.h>
5#include <linux/ns_common.h>
6#include <linux/fs_pin.h>
7
8extern struct list_head notify_list;
9
10struct mnt_namespace {
11 struct ns_common ns;
12 struct mount * root;
13 struct {
14 struct rb_root mounts; /* Protected by namespace_sem */
15 struct rb_node *mnt_last_node; /* last (rightmost) mount in the rbtree */
16 struct rb_node *mnt_first_node; /* first (leftmost) mount in the rbtree */
17 };
18 struct user_namespace *user_ns;
19 struct ucounts *ucounts;
20 wait_queue_head_t poll;
21 u64 seq_origin; /* Sequence number of origin mount namespace */
22 u64 event;
23#ifdef CONFIG_FSNOTIFY
24 __u32 n_fsnotify_mask;
25 struct fsnotify_mark_connector __rcu *n_fsnotify_marks;
26#endif
27 unsigned int nr_mounts; /* # of mounts in the namespace */
28 unsigned int pending_mounts;
29 refcount_t passive; /* number references not pinning @mounts */
30} __randomize_layout;
31
32struct mnt_pcp {
33 int mnt_count;
34 int mnt_writers;
35};
36
37struct mountpoint {
38 struct hlist_node m_hash;
39 struct dentry *m_dentry;
40 struct hlist_head m_list;
41};
42
43struct mount {
44 struct hlist_node mnt_hash;
45 struct mount *mnt_parent;
46 struct dentry *mnt_mountpoint;
47 struct vfsmount mnt;
48 union {
49 struct rb_node mnt_node; /* node in the ns->mounts rbtree */
50 struct rcu_head mnt_rcu;
51 struct llist_node mnt_llist;
52 };
53#ifdef CONFIG_SMP
54 struct mnt_pcp __percpu *mnt_pcp;
55#else
56 int mnt_count;
57 int mnt_writers;
58#endif
59 struct list_head mnt_mounts; /* list of children, anchored here */
60 struct list_head mnt_child; /* and going through their mnt_child */
61 struct mount *mnt_next_for_sb; /* the next two fields are hlist_node, */
62 struct mount * __aligned(1) *mnt_pprev_for_sb;
63 /* except that LSB of pprev is stolen */
64#define WRITE_HOLD 1 /* ... for use by mnt_hold_writers() */
65 const char *mnt_devname; /* Name of device e.g. /dev/dsk/hda1 */
66 struct list_head mnt_list;
67 struct list_head mnt_expire; /* link in fs-specific expiry list */
68 struct list_head mnt_share; /* circular list of shared mounts */
69 struct hlist_head mnt_slave_list;/* list of slave mounts */
70 struct hlist_node mnt_slave; /* slave list entry */
71 struct mount *mnt_master; /* slave is on master->mnt_slave_list */
72 struct mnt_namespace *mnt_ns; /* containing namespace */
73 struct mountpoint *mnt_mp; /* where is it mounted */
74 union {
75 struct hlist_node mnt_mp_list; /* list mounts with the same mountpoint */
76 struct hlist_node mnt_umount;
77 };
78#ifdef CONFIG_FSNOTIFY
79 struct fsnotify_mark_connector __rcu *mnt_fsnotify_marks;
80 __u32 mnt_fsnotify_mask;
81 struct list_head to_notify; /* need to queue notification */
82 struct mnt_namespace *prev_ns; /* previous namespace (NULL if none) */
83#endif
84 int mnt_t_flags; /* namespace_sem-protected flags */
85 int mnt_id; /* mount identifier, reused */
86 u64 mnt_id_unique; /* mount ID unique until reboot */
87 int mnt_group_id; /* peer group identifier */
88 int mnt_expiry_mark; /* true if marked for expiry */
89 struct hlist_head mnt_pins;
90 struct hlist_head mnt_stuck_children;
91 struct mount *overmount; /* mounted on ->mnt_root */
92} __randomize_layout;
93
94enum {
95 T_SHARED = 1, /* mount is shared */
96 T_UNBINDABLE = 2, /* mount is unbindable */
97 T_MARKED = 4, /* internal mark for propagate_... */
98 T_UMOUNT_CANDIDATE = 8, /* for propagate_umount */
99
100 /*
101 * T_SHARED_MASK is the set of flags that should be cleared when a
102 * mount becomes shared. Currently, this is only the flag that says a
103 * mount cannot be bind mounted, since this is how we create a mount
104 * that shares events with another mount. If you add a new T_*
105 * flag, consider how it interacts with shared mounts.
106 */
107 T_SHARED_MASK = T_UNBINDABLE,
108};
109
110#define MNT_NS_INTERNAL ERR_PTR(-EINVAL) /* distinct from any mnt_namespace */
111
112static inline struct mount *real_mount(struct vfsmount *mnt)
113{
114 return container_of(mnt, struct mount, mnt);
115}
116
117static inline int mnt_has_parent(const struct mount *mnt)
118{
119 return mnt != mnt->mnt_parent;
120}
121
122static inline int is_mounted(struct vfsmount *mnt)
123{
124 /* neither detached nor internal? */
125 return !IS_ERR_OR_NULL(ptr: real_mount(mnt)->mnt_ns);
126}
127
128extern struct mount *__lookup_mnt(struct vfsmount *, struct dentry *);
129
130extern int __legitimize_mnt(struct vfsmount *, unsigned);
131
132static inline bool __path_is_mountpoint(const struct path *path)
133{
134 struct mount *m = __lookup_mnt(path->mnt, path->dentry);
135 return m && likely(!(m->mnt.mnt_flags & MNT_SYNC_UMOUNT));
136}
137
138extern void __detach_mounts(struct dentry *dentry);
139
140static inline void detach_mounts(struct dentry *dentry)
141{
142 if (!d_mountpoint(dentry))
143 return;
144 __detach_mounts(dentry);
145}
146
147static inline void get_mnt_ns(struct mnt_namespace *ns)
148{
149 ns_ref_inc(ns);
150}
151
152extern seqlock_t mount_lock;
153
154DEFINE_LOCK_GUARD_0(mount_writer, write_seqlock(&mount_lock),
155 write_sequnlock(&mount_lock))
156DEFINE_LOCK_GUARD_0(mount_locked_reader, read_seqlock_excl(&mount_lock),
157 read_sequnlock_excl(&mount_lock))
158
159struct proc_mounts {
160 struct mnt_namespace *ns;
161 struct path root;
162 int (*show)(struct seq_file *, struct vfsmount *);
163};
164
165extern const struct seq_operations mounts_op;
166
167extern bool __is_local_mountpoint(const struct dentry *dentry);
168static inline bool is_local_mountpoint(const struct dentry *dentry)
169{
170 if (!d_mountpoint(dentry))
171 return false;
172
173 return __is_local_mountpoint(dentry);
174}
175
176static inline bool is_anon_ns(struct mnt_namespace *ns)
177{
178 return ns->ns.ns_id == 0;
179}
180
181static inline bool anon_ns_root(const struct mount *m)
182{
183 struct mnt_namespace *ns = READ_ONCE(m->mnt_ns);
184
185 return !IS_ERR_OR_NULL(ptr: ns) && is_anon_ns(ns) && m == ns->root;
186}
187
188static inline bool mnt_ns_attached(const struct mount *mnt)
189{
190 return !RB_EMPTY_NODE(&mnt->mnt_node);
191}
192
193static inline bool mnt_ns_empty(const struct mnt_namespace *ns)
194{
195 return RB_EMPTY_ROOT(&ns->mounts);
196}
197
198static inline void move_from_ns(struct mount *mnt)
199{
200 struct mnt_namespace *ns = mnt->mnt_ns;
201 WARN_ON(!mnt_ns_attached(mnt));
202 if (ns->mnt_last_node == &mnt->mnt_node)
203 ns->mnt_last_node = rb_prev(&mnt->mnt_node);
204 if (ns->mnt_first_node == &mnt->mnt_node)
205 ns->mnt_first_node = rb_next(&mnt->mnt_node);
206 rb_erase(&mnt->mnt_node, &ns->mounts);
207 RB_CLEAR_NODE(&mnt->mnt_node);
208}
209
210bool has_locked_children(struct mount *mnt, struct dentry *dentry);
211struct mnt_namespace *get_sequential_mnt_ns(struct mnt_namespace *mnt_ns,
212 bool previous);
213
214static inline struct mnt_namespace *to_mnt_ns(struct ns_common *ns)
215{
216 return container_of(ns, struct mnt_namespace, ns);
217}
218
219#ifdef CONFIG_FSNOTIFY
220static inline void mnt_notify_add(struct mount *m)
221{
222 /* Optimize the case where there are no watches */
223 if ((m->mnt_ns && m->mnt_ns->n_fsnotify_marks) ||
224 (m->prev_ns && m->prev_ns->n_fsnotify_marks))
225 list_add_tail(new: &m->to_notify, head: &notify_list);
226 else
227 m->prev_ns = m->mnt_ns;
228}
229#else
230static inline void mnt_notify_add(struct mount *m)
231{
232}
233#endif
234
235static inline struct mount *topmost_overmount(struct mount *m)
236{
237 while (m->overmount)
238 m = m->overmount;
239 return m;
240}
241
242static inline bool __test_write_hold(struct mount * __aligned(1) *val)
243{
244 return (unsigned long)val & WRITE_HOLD;
245}
246
247static inline bool test_write_hold(const struct mount *m)
248{
249 return __test_write_hold(val: m->mnt_pprev_for_sb);
250}
251
252static inline void set_write_hold(struct mount *m)
253{
254 m->mnt_pprev_for_sb = (void *)((unsigned long)m->mnt_pprev_for_sb
255 | WRITE_HOLD);
256}
257
258static inline void clear_write_hold(struct mount *m)
259{
260 m->mnt_pprev_for_sb = (void *)((unsigned long)m->mnt_pprev_for_sb
261 & ~WRITE_HOLD);
262}
263
264struct mnt_namespace *mnt_ns_from_dentry(struct dentry *dentry);
265